1. A method for constructing machinery flumes comprising:
fabricating a plurality of flume sections, each of said plurality of sections having at least one flume lining forming a channel and a rebar frame external of said channel;
precasting a concrete sheath over said lining and said rebar frame of each section, a portion of said at least one lining portion extending beyond an end of said form, and
coupling a first section of said plurality of sections by positioning said extending portion of said first section lining to overlay an end of a second of said plurality of flume sections, and by joining said extended portion overlay in said channel of said second flume section.
2. The invention as described in claim 1 wherein said lining includes a primary wall and a secondary wall.
3. The invention as described in claim 1 wherein said positioning includes lowering said first and second sections in an excavation.
4. The invention as described in claim 3 wherein said lowering comprises hoisting a spreader beam.
5. The invention as described in claim 4 wherein said spreader beam is an I-beam.
6. The invention as described in claim 1 and wherein said precasting including embedding anchors on said concrete layer.
7. A flume comprising:
a plurality of flume sections, each section having a lining supported in a reinforcement frame embedded in a precast concrete layer, and having an end of said lining extending beyond an edge of said precast concrete layer, an edge of said precast concrete layer having a key-way, an opposite edge of said precast concrete layer having a keying rim,
an end to end alignment of precast concrete sections and
a seal embedded between said edge of said precast concrete layer and said opposite edge of said precast concrete layer adjacent to said edge.
8. A flume as described in claim 7 and further comprising an excavation receiving each said flume section, said excavation having a width not substantially more than the width of said sections.
9. A method for constructing machinery flumes comprising:
constructing a plurality of flume sections;
each of said plurality of sections having at least one flume lining forming a channel;
securing said lining to a frame having a predetermined footing dimension below the channel;
precasting a concrete sheath about said lining and imbedding said frame, in a form, a portion of said at least one lining portion extending beyond one end of said sheath,
coupling a first precast section by positioning said extending portion to overlap an end of a second precast section.
10. The invention as described in claim 9 wherein said predetermined footing dimension of said first precast section and said predetermined footing dimension of said second precast section comply with a predetermined slope for the flume lining.
11. The invention as described in claim 9 and comprising installing said first and second precast sections in an excavation.
12. The invention described in claim 11 and comprising supporting said first and second precast sections by backfilling said excavation.
13. A method for constructing machinery flumes by installing precast sheathed, flume liner sections in an excavation, comprising:
installing at least one rigid support across the channel of the liner of each said precast sheathed section;
suspending said precast sheathed section by lifting said at least one rigid support; and
lowering said precast sheathed section into an excavation to position said liner at a predetermined height with respect to a benchmark; and
further comprising lowering a second precast sheathed section having an extended liner portion adjacent said first precast sheathed section so that said extended liner portion overlaps said first precast sheathed section liner.
14. The invention as described in claim 13 wherein said precast sheathed section includes an embedded frame, and wherein said frame includes a footing at a predetermined dimension from said liner.
15. The invention as described in claim 13 and comprising joining said extended portion to said overlapped portion in said channel.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
We claim:
1. A circuit for three-phase electric conversion, comprising:
a main switching circuit comprising a plurality of main switches connected between a power rail and a ground rail;
an auxiliary switching circuit comprising a plurality of auxiliary switches connected between said plurality of main switches and one of said power rail and said ground rail, said plurality of auxiliary switches being half in number of said plurality of main switches.
2. A circuit for three-phase electric conversion as recited in claim 1 wherein each of said auxiliary switches is connected to a pair of said main switches through a resonant tank circuit.
3. A circuit for three-phase electric conversion as recited in claim 1,
wherein said plurality of main switches comprises six main switches, and
wherein said plurality of auxiliary switches comprises three auxiliary switches.
4. A circuit for three-phase electric conversion as recited in claim 1, wherein said plurality of main switches comprises six main switches arranged in three pairs, and
wherein said plurality of auxiliary switches comprises three auxiliary switches.
5. A circuit for three-phase electric conversion as recited in claim 4 further comprising:
a resonant tank comprising a series connected inductor and capacitor connected between each of said auxiliary switches and to each said pair of main switches.
6. An electric conversion circuit, comprising:
a three phase alternating current terminal;
a direct current terminal connected between a positive rail and a negative rail;
a main switching circuit comprising:
three pairs of main switches connected between said positive rail and said negative rail, a center point between each main switch pair comprising said three phase alternating current terminal; and
parallel diodes connected across each of said main switches;
an auxiliary switching circuit comprising:
three pairs of auxiliary diodes connected between said positive rail and said negative rail; and
three auxiliary switches each connected at a first end to one of said positive rail and said negative rail and at a second end to a center point of a respective one of said three pairs of auxiliary diodes; and
an resonant tank circuit connecting said main switching circuit and said auxiliary switching circuit.
7. An electric conversion circuit as recited in claim 6 wherein said resonant tank circuit comprises three pairs of an inductor and a capacitor connected in series.
8. An electric conversion circuit as recited in claim 6 wherein said conversion circuit is an inverter when a DC source is connected to said direct current terminal and a load is connected to said a three phase alternating current terminal.
9. An electric conversion circuit as recited in claim 6 wherein said conversion circuit is a rectifier when a DC load is connected to said direct current terminal and an AC source is connected to said a three phase alternating current terminal.